Nigerian billionaire philanthropist Gilbert Chagoury, who has been a major donor of the Clinton Foundation, was denied entry to the U.S. last year due to suspected ties to the Lebanese terror group Hezbollah.

Chagoury, 70, has been friendly with former President Bill Clinton and his wife, current presidential candidate Hillary Clinton, since the 1990s, and has donated between $1 million and $5 million to the couple’s foundation, according to the Los Angeles Times.

Chagoury has been a close ally of former Nigerian dictator Gen. Sani Abacha and has tried to influence U.S. policy in the dictator’s favor. The State Department has also been investigating the billionaire, who has Lebanese roots, for his ties to Lebanon. He is currently on a no-fly list, in part because of his connection to Lebanese Christian politician and former Lebanese Army commander Michel Aoun, whose party had signed a memorandum of understanding with Hezbollah in 2006.

A 2013 FBI intelligence report has indicated that Chagoury provided funding to Aoun funds, which Aoun transferred to Hezbollah. When Chagoury applied for a tourist visa in the summer of 2015, the state department denied his request on grounds related to funding terrorism. Chagoury denies any link to Hezbollah.